Heating, ventilation and air conditioning (HVAC) systems have existed in vehicles for decades. In typical HVAC systems, a compressor is connected to an engine crankshaft by a belt or the like such that the compressor rotates with the engine. Rotation of the compressor compresses and circulates refrigerant or other fluid throughout the HVAC system. In conventional non-hybrid, engine-only vehicles, the speed of the compressor depends on the speed of the crankshaft.
HVAC systems have evolved with the corresponding popularity of hybrid-electric vehicles (HEVs) or battery-electric vehicles (BEVs). In such vehicles, a separate compressor motor (powered by a battery) may operate the compressor. This allows the compressor to be operated at controllable varying speeds, and entirely separate from the various powertrain components, such as the crankshaft.